Arrangement for simultaneously interrogating a plurality of portable radio frequency communication devices

ABSTRACT

An updatable, interrogation system is provided for simultaneously interrogating a plurality of portable data cards. Operable over a plurality of radio frequencies, the interrogation system sequentially communicates with each portable data card as it comes within communication range on a first one of the plurality of radio frequencies for determining a unique identification number associated with each data card. Once the identification number for a card is obtained by the interrogation system, a predetermined transaction, such as deactivating an electronic barrier to entering a limited access area, for the holder of the identified card is initiated. The interrogation system then selects and moves with each card to a different one of the plurality of radio frequencies for completing a data transfer portion of the transaction. The interrogation system simultaneously completes each predetermined transaction of reading from and writing data to each one of the plurality of cards while communicating with each card on the respectively selected ones of the plurality of radio frequencies.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a system which uses smart cards, and moreparticularly, to a system which uses smart cards for processing andcommunicating data while in a mobile environment.

2. Description of the Prior Art

Wireless technology is fueling a major revolution in communications.This technology allows new access connections to landline networks.However, the impact of wireless is far more profound than simply beinganother method of access. Wireless technology allows the customer tohave mobility in his or her communications and not be constrained to thetether of wired access. Wireless technology also permits the customer togain access to an application from wherever he or she wishes, within theconstraints of wireless network deployment and range.

What is still in its infant stages, however, is wireless communicationswhich enables a user of a smart card-like device to become completelyuntethered when using such a device in short range wirelesscommunications.

A number of proposals have been made with regard to providing a customerwith a wireless connection for performing various financialtransactions. One such proposal, for example, is described in U.S. Pat.No. 4,977,501 which issued to J. P. Lefevre on Dec. 11, 1990. Thispatent describes a fare collection system for operators of transportvehicles wherein information is periodically exchanged at microwavefrequencies between a smart card-like ticket, held by a passenger in thevehicle, and a transceiver also in the vehicle. A credit balanceinitially assigned to the ticket is decremented by circuitry in thetransceiver which interrogates the ticket.

Other proposals have also been made with regard to providing a holder ofa smart card-like device with an identifying radio frequency signalwhich uniquely identifies the individual holder of the device. Oneproposed wireless system for providing a radio frequency emittingidentifier is described in U.S. Pat. No. 4,384,288 issued to C. A.Walton on May 17, 1983. This patent describes an electronicidentification system comprising a credit card-shaped identifier whichgenerates a programmable pulse position-modulated signal in the radiofrequency range for identification of the user.

It is becoming increasingly necessary to quickly and accurately identifypeople located at a terminal remote to a central processing station.Such identification is necessary for making financial transactions orfor expediting the movement of people through electronic barriers. Insuch systems, the identification must be accurate and, to conservecomputer time, done relatively quickly.

As wireless communication matures, it will become more and more likelythat multiple smart card-like devices will be in radio range of acommunication terminal thereby causing destructive interference, even ifonly short range communications are allowed. It is desirable, therefore,to have a wireless interrogatable and updatable system which supportsmultiple smart card-like devices within radio range without destructiveinterference.

SUMMARY OF THE INVENTION

The prior art problem is solved in accordance with the present inventionby providing an updatable, interrogation system which simultaneouslyinterrogates a plurality of portable data cards.

Operable over a plurality of radio frequencies, in accordance with theprinciples of the invention, the interrogation system sequentiallycommunicates with each portable data card as it comes within radio rangeon a first one of the plurality of radio frequencies. On this radiofrequency, the interrogation system determines a unique identificationnumber associated with each data card. Once the identification numberfor a card is obtained by the interrogation system, a predeterminedtransaction, such as deactivating an electronic barrier to entering alimited access area, for the holder of the identified card is initiated.

In further accordance with the principles of the invention, theinterrogation system selects and moves with each card to a different oneof the plurality of radio frequencies for completing with the card adata transfer portion of the predetermined transaction. While on thisselected one of the plurality of radio frequencies, the interrogationsystem completes the predetermined transaction of reading data from andwriting data to the card while simultaneously communicating with otherof the plurality of cards on the respectively selected ones of theplurality of radio frequencies for these cards.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention and its mode of operation will be more clearly understoodfrom the following detailed description when read with the appendeddrawing in which:

FIG. 1 is a block diagram of an interrogator system for interfacing withmultiple smart cards and radio frequency jackets in accordance with thepresent invention;

FIG. 2A is a view of the top surface of one of the radio frequencyjackets illustrated in FIG. 1;

FIG. 2B is a side view of the radio frequency jacket illustrated in FIG.2A;

FIG. 2C is the top surface view of one of the smart cards illustrated inFIG. 1;

FIG. 3A is a top view of a radio frequency jacket and a smart card asthey appear when the smart card is inserted into the jacket;

FIG. 3B is one side view of the arrangement of FIG. 3A;

FIG. 3C is another side view of the arrangement of FIG. 3A;

FIG. 4 is a block diagram of an exemplary site transmitter interface forthe interrogator system of FIG. 1;

FIG. 5 is an exemplary time frame format for use in the presentinterrogator system;

FIG. 6 is a block diagram of an exemplary site receiver interface in forthe interrogator system of FIG. 1;

FIG. 7 is a block diagram of exemplary interface circuitry in the radiofrequency jacket for providing communications between the interrogatorand the smart card, in accordance with the present invention;

FIG. 8 is a simplified diagram for illustrating the interaction betweenthe interrogator, the jacket and the smart card for facilitating two-wayradio frequency read/write communications, in accordance with thepresent invention; and

FIG. 9 is a block diagram of an alternative interrogator system forinterfacing with multiple smart cards and radio frequency jackets inaccordance with the present invention;

Throughout the drawing, the same elements when shown in more than onefigure are designated by the same reference numerals.

DETAILED DESCRIPTION

The present invention relates to an interrogator system for smart cardsand more particularly, to an interrogator system for smart cards capableof processing and communicating data while in a mobile environment. Theinterrogator system is capable of handling large volumes of traffic andwill advantageously expedite the movement of people or moving objectshaving the smart cards attached thereto through electronic barriers. Theusers of the interrogator system communicate through radio frequencies(RF) with one of any of a plurality of interrogation station sites(SITEs) located in the vicinity of an electronic barrier choke point,such as a turnstile, inserted in a designated passageway for users ofthe system.

Referring now to FIG. 1, there is shown an illustrative block diagram ofan interrogator 10, including a plurality of N SITES 11₁ through 11_(N)geographically dispersed, and their respective antennas 12, a controller16 and a host 17. Also illustrative shown in FIG. 1, but is not a partof the interrogator 10 are smart cards 20, which are the size of astandard credit card, and pocket size enclosures or RF jackets 40 forholding each of the smart cards and providing smart card interfacecircuitry. It is to be understood that the smart card interfacecircuitry for communicating with the N SITES 11₁ through 11_(N) couldalso be totally located on the card rather than in the pocket sizeenclosure or RF jacket as described herein.

The host 17 is typically a data base of a provider of a particularservice on the smart card 20. The controller 16 may be colocated with orseparated from the host 17 and contains switching, control, and all linecircuits required by the host 17 for establishing, maintaining andterminating communications between the interrogator 10 and the RF jacket40 and smart card 20. The jacket 40 performs a multitude of functionsincluding providing operating power in the form of magnetic energycoupled from the jacket to the card 20, and also coupling data betweenthe interrogator 10 and the card 20. Communications between theinterrogator 10 and each of the RF jackets 40 may take place througheither of the illustrated antennas 12.

Each smart card/jacket combination contains an associated RF transceiver420, described later herein with reference to FIG. 7, which communicatessignaling and data information within, for example, the 2.4 GHzfrequency band. This data and signaling information may be communicatedto any one of the plurality of N SITEs 11₁ through 11_(N). The pluralityof N SITEs are strategically distributed near designated passagewaysinto which users of the smart card/jacket combination jacket arefunneled. These passageways are sufficiently near the radiation sourceprovided by one of the antennas 12 so that normal movement of theseusers will allow adequate time for complete interrogating of and anynecessary writing to the card.

Each SITE 11_(i) may be accessed by, for example, up to M_(i)simultaneous users, typically between 20 and 30, while located in itsproximity. Communication between the M_(i) users and the SITEs 11_(i)may be accomplished, for example, by Time Division Multiple Access(TDMA), Frequency Division Multiple Access (FDMA), the slotted ALOHAprotocol or any other suitable method which avoids interference at aSITE while communicating with the multiple simultaneous users. Forpurposes of discussion, and not for purposes of limitation, it will beassumed hereinafter that the interrogator system uses FDMA techniquesfor communicating with the M_(i) users.

Operable over a plurality of RF channels, the interrogator systeminitially sequentially communicates with each smart card/jacketcombination on a first common or set-up one of the plurality of RFchannels as the smart card/jacket combination comes within communicationrange of a SITE antenna 12.

On this first RF channel, the interrogator system determines a uniqueidentification number associated with each card in the card/jacketcombination. Once the identification number for a card is obtained bythe interrogator system, a predetermined transaction for the holder ofthe identified card is initiated.

The interrogator system next selects a second one from the plurality ofRF channels and moves with each card/jacket combination to this selectedone of the plurality of RF channels for completing a data transferportion of the predetermined transaction. The interrogator system thencompletes each predetermined transaction of reading and writing data tothe card/jacket combination while simultaneously communicating with eachcard/jacket combination on its respectively selected one of theplurality of RF channels. With the frequency division multiplexingarrangement employed by the interrogator system, a large volume ofcard/jacket users are easily handled and the movement of these usersthrough designated electronic barrier choke points is advantageouslyexpedited.

In an area where there is almost always a small volume of traffic, oneor two electronic barrier choke points, such as turnstiles, may beemployed. Accordingly, a single SITE 11_(i) may be used forcommunications between the interrogator 10 and the plurality of M_(i)users. In other areas where large volumes of traffic are periodicallyexpected, such as during rush hour on a subway, many electronic barrierchoke points are provided. The plurality of SITEs 11_(i) are accordinglyincreased to expedite the movement of people through these electronicbarriers.

Although communication between the SITEs 11_(i) and the controller 16may be achieved using a number of suitable methods, for purposes ofdiscussion, and not for purposes of limitation, it will be assumedhereinafter that (a) the interrogator system 10 uses TDMA techniquesalong a bus; (b) each SITE 11_(i) processes the signals from the userslocated thereat into separate packets of information, includingnecessary control information, for transmission on a bus 14 to the database illustratively shown as host 17; and (c) the interrogator system 10uses an optical local area network (LAN) transmitting lightwave signalsalong a bus 14 which is an optical waveguide such as a single modeoptical fiber bus. Such a system is available in the art and isdescribed in U.S. Pat. No. 4,807,222 which issued to N. Amitay on Feb.21, 1989. TDMA techniques are also known and are described in, forexample, U.S. Pat. Nos. 4,143,241, 4,232,266, 4,232,197, 4,188,578,4,730,305, and 4,730,310.

The interrogator 10 of FIG. 1 employs a serial open-ring networkarrangement. In this arrangement, a frame marker generator 18 is locatedat the headend of a bus 14 for dividing the time on bus 14 into equalframes of duration T, as shown in FIG. 5. The markers transmitted byframe marker generator 18 at the beginning of each frame serve as asource of synchronization for the entire network and consist of aperiodic light modulated sequence of bits, of duration δ T, transmittedevery T seconds, with δ T<<T. This function can also be incorporated ona standby basis within the first few SITEs along bus 14 to increase thereliability of the system in case of a failure of the frame markergenerator 18 at the head-end of bus 14. Alternatively, the frame markingfunction can be directly performed within the first SITE 11_(i) in placeof frame marker generator 18 with the next few succeeding SITEsproviding standby operation. Each of the SITEs 11d to 11_(N)appropriately formats the signals from each of the M users locatedthereat into separate packets of information and, after detecting themarkers from frame marker generator 18 and then sensing that a frame isnot being used by previous SITEs on bus 14, the SITE transmits a packetof information onto bus 14 during a detected empty frame period.

Referring next to FIGS. 2A, 2B, 2C and 3A, 3B, 3C, in combination, thereare shown the basic structures of the jacket 40 and the smart card 20.The smart card 20 typically is a personal memory card or data card whichis usable in a variety of applications, from custom repertory dialing tostorage of individual medical and/or banking records. Although the cardlooks and feels much like an ordinary credit card, the smart cardincludes a computer, an electrically erasable field-programmableread-only memory and also circuitry for inductively receiving a powersignal and capacitive transferring data signals between the card andassociated card reader/writer circuitry within the interface circuitrylocated in the jacket 40. No direct ohmic electrical contact is madebetween the card and the reader/writer circuitry in the jacket fortransferring power to the card 20 via the reader/writer circuitry or fortransferring data to and from the card. The card is also reprogrammableby a specially designated interrogator 10 via the reader/writercircuitry in the jacket 40 with new and different data as desired.

Memory cards suitable for use as smart card 20 are known in the art andcommercially available from AT&T and other suppliers. Such cards alsoare described in U.S. Pat. No. 4,795,898 which issued to H. L. Bernsteinet al. on Jan. 3, 1989; U.S. Pat. No. 4,816,653 which issued to E. C.Anderl et al. on Mar. 28, 1989; and U.S. Pat. No. 4,882,474 which issuedto E. C. Anderl et al. on Nov. 21, 1989. A card reader/writer suitablefor use as the reader/writer circuitry in the jacket 40 is described inU.S. Pat. No. 4,798,322 which issued to H. L. Bernstein et al. on Jan.17, 1989.

The jacket 40 includes a sleeve-like opening adapted to receive andposition the smart card 20 for providing the operating power from thejacket to the card and also for enabling read/write communicationsbetween the card 20 and the associated interrogator 10. Normally held inthe off-state, radiated energy from an interrogation SITE associatedwith the interrogator 10 turns on the jacket's internal battery operatedpower supply when the smart card/jacket combination is within a few feetof the radiation source at the interrogation SITE. A holder of thesmart/card jacket combination is able to conduct, or have conducted forhim or her as appropriate, a data transaction with the interrogator 10either while standing near or moving through an interrogation SITE forthe interrogator. When the smart card/jacket combination is outside ofthe field of the radiated energy from the interrogation SITE, power toall the circuitry in the jacket and the card are turned off, therebyextending the operating life for the battery operated power supply.

The top surface and a side view of the jacket 40 are depicted in FIGS.2A and 2B. Also, the smart card 20 is also shown in FIG. 2C, whileremoved from the jacket 40. The jacket 40 includes a battery 401 forproviding operating power for the electronics therein and for providingoperating power to the smart card 20. An optional liquid crystal display(LCD) 405 may be provided on the top surface of the jacket 40 forinforming the holder of the card of the results of a particulartransaction. Although not shown, a keypad may also be provided on thetop surface of the jacket 40 if desired.

The smart card 20 is depicted inserted in the jacket 40 in FIGS. 3A, 3Band 3C. An edge of the card extends slightly beyond the right surface ofthe jacket 40, as depicted in FIGS. 3A and 3C, to facilitate the removaland insertion of the card into this jacket.

Referring once again to the interrogator 10, there is shown in FIG. 4 ablock diagram of a transmitter section for a SITE 11_(i) which receivesits signal from bus 14. In the transmitter section of FIG. 4 a smallpart of the light-modulated bit stream from serial bus 14 is demodulatedby a photo detector 110 to, for example, baseband. This demodulatedsignal is received by both a clock and frame recovery circuit 111 and anempty frame detector 112. Clock and frame recovery circuit 111 functionsto recover the frame markers generated by frame marker generator 18 (inFIG. 1 ) out of which a bit clock is generated. The empty frame detector112 receives the recovered frame markers from recovery circuit 111 andscan the frame during the time interval t_(o), shown in FIG. 5, todetermine whether the frame is occupied or not by a packet ofinformation transmitted by one of the prior SITEs 11 on bus 14. Timeinterval t_(o) may typically be δ T plus a few bits in duration, ort_(o) approximates δ T.

If the frame is occupied with a packet of information transmitted by oneof the preceding SITEs 11, this packet of information will continuetraveling on bus 14, in the arrangement of FIG. 4, through analog delay113 preferably with very low attenuation. If attenuation is too great, alaser light source (not shown) may be employed for amplifying andsending the modulated packet of information forward.

If one or more users in the arrangement of FIG. 4 has transmitted asignal to a SITE 11_(i), this signal is received by the SITE's antenna12 for delivery to a receiver 117. It is to be understood that all users1-M_(i) can transmit asynchronously at a SITE 11_(i) using any suitabletechnique described hereinbefore, and that receiver 117 is arranged toreceive such asynchronously transmitted signals and process themseparately. Receiver 117 functions to collect the information receivedfrom each user, formats the information of each user by adding anyrequired overhead protocol, buffers the formatted packet(s) ifnecessary, and transmits each formatted packet to a transmitter buffer118 at the appropriate time.

Upon the receipt of a "Load" enable signal from empty frame detector112, transmitter buffer 118 transfers the packet stored therein in aparallel manner into a very fast shift register 115. When empty framedetector 112 generates a "shift" enable signal, the packet in shiftregister 115 is delivered in serial fashion to modulator laser 116 atthe bit clock rate from the clock and frame recovery circuit 111 fortransmission onto serial bus 14. The delay D in FIG. 5, which is analogin the arrangement of FIG. 4 is of sufficient duration to enable themultiplexing of a packet of information from transmitter buffer 118 intoa frame on the bus once that same frame is determined to be unoccupied.The delay D is approximately equal to t_(o) plus, for example, up to 20bits in duration.

This interface protocol is collision-free and, therefore, veryefficient. As long as there is a packet of information available fortransmission in the transmitter buffer 118, it will be multiplexed ontobus 14 in the immediately detected unoccupied frame. When a packet ofinformation becomes available in the transmitter buffer 118 past thedecision of an unoccupied frame by empty frame detector 112, it willhave to wait until the next unoccupied frame comes along.

Referring next to FIG. 6, there is shown the architecture of thereceiver section of an SITE 11_(i) for the network arrangement ofFIG. 1. In this section, a small portion of the light modulated bitstream propagating along bus 14 is received by a photo detector 120 viaan R-directional coupler 121. Photo detector 120 functions in the mannerdescribed for photo detector 110 in the transmit section of a SITE 11.The demodulated signal from photo detector 120 is delivered to both aclock and frame detector circuit 122, which recovers the clock and framemarkers from the received bit stream, and a very fast shift register 123into which the received bit stream is serially fed. In response toenable signals from detector 122, register 123 is unloaded in parallelinto a message decoder and buffer 124.

In the message decoder and buffer 124 a decision is made, based upon theaddress or destination provided in the overhead portion of the packet ofinformation, whether to discard or store the message in an includedbuffer. More particularly, if a packet of information includes anaddress destination for one of the users then associated with thisparticular SITE, the packet of information is buffered, otherwise it isdiscarded. Messages stored in decoder and buffer 124 are then modulatedin a low power radio frequency transmitter and modulator 125 andbroadcasted by antenna 12, to all users then associated with thatparticular SITE.

Referring next to FIG. 7, there is shown a high level block diagram ofthe interface circuitry in the jacket 40 for providing communicationsbetween the interrogator 10 and the smart card 20. The interrogator 10continually radiates a low level interrogating signal, typically on afrequency channel at 2.4 GHz. This signal is radiated at a levelsufficient to generate an electrical field reflective of a desired sizeof an area of operation for each interrogation SITE.

While outside an area of operation for an interrogation SITE, the jacket40 is maintained in a completely OFF state. While in this state, thereis no requirement for signal monitoring electronics to be maintained inthe active state. Thus standby current consumption is eliminated and thelife of the battery 401 in the jacket 40 is substantially prolonged.Alternatively, if a rechargeable battery is employed as battery 401, thetime between charges of this battery is substantially increased. Thisadvantageous operation is achieved by a detector circuit 440 describedin a copending U.S. patent application Ser. No. 08/086401, filed on Jul.6, 1993. Through use of this detector circuit, all current consumingcircuits in the jacket and card are permitted to remain completely offwhile the jacket is outside an area of operation for an interrogationSITE.

As a holder of the card and jacket enters an area of operation of theinterrogator 10, the radio frequency signal energy radiated by anantenna 12, at an interrogation SITE for the interrogator 10 is capturedby the antenna 410. This energy is coupled to the radio-frequency (R/F)section 420 which is used by the jacket 40 in transmitting data to andreceiving data from the interrogator 10. This captured energy is alsocoupled through the R/F section 420 to the detector circuit 440, whichprovides a means for configuring a central processing unit CPU 430 froman OFF state to a full ON operating state. Thus the captured energy onthe antenna 410, while the jacket 40 is in an area of operation of theinterrogator 10, activates the detector 440.

The CPU 430 advantageously provides a number of control functions. Itprovides, for example, a means for interfacing the smart card 20 to theinterrogator 10. Operating under firmware control provided by itsinternal ROM, the CPU 430 formats data provided to the smart card 20 viathe data conditioning circuit 450 and to the interrogator 10 via the R/Fsection 420. The CPU 430 also interprets commands from the interrogator10 received through the R/F section 420 as appropriate. In addition, theCPU 430 checks for errors in reading and writing data to the smart card20 and in transmissions to and from the interrogator 10.

The data conditioning circuit 450 receives serial data from the CPU 430and differentially drive capacitive plates 451 and 452 which interfacewith respectively aligned capacitive plates (not shown) in the smartcard 20. The data conditioning circuit 450 converts the serial data fromthe CPU 430 which is of one polarity, into a differential polarity suchthat for each transition of the signal from the CPU 430, a potential onone of the capacitive plates goes positive, while a potential on theother capacitive plate goes negative.

The data conditioning circuit 450 also receives differential data fromthe capacitive plates (not shown) in the smart card 20 that are broughtin close proximity with and aligned with the capacitive plates 453 and454 in the jacket 40. This data from the smart card 20 is coupled to theCPU 430 in the jacket 40 for coupling on to the interrogator 10.

Hysteresis is built into the data conditioning circuit 450 such that adifferential pulse greater than the hysteresis is all that is requiredto switch the output of the data conditioning circuit 450 to thecapacitive plates 451 and 452 from a high state to a low state or from alow state to a high state. The hysteresis also aids in preventing noisefrom causing false triggering of receive circuitry in the dataconditioning circuit while receiving data from the smart card 20 byignoring small differential noise signals and switching only on largedifferential data signals. Thus once the receive circuitry in the dataconditioning circuit 450 switches states, if there is no further input,this receive circuitry will remain in whatever state it is then switchedinto and not drift back to the other state.

The CPU 430 also provides a means for activating the smart card 20. Oncethe CPU 430 enters the full ON operating state, it provides an actuationsignal to a flexible wafer inductor (FWID) drive circuit 460. Thiscircuit receives its power from the battery 401 which has the voltagestepped up to an appropriate operating level by a DC to DC convertercircuit 402. Power to the card 20 is provided from the FWID drivecircuit 460 via a FWID 461 which comprises the primary winding of atransformer. This primary winding comprises a multiturn coil ofelectrically conductive material and a ferrite core positioned to directthe transmission of magnetic energy into a flat multiturn coil (notshown) located in the smart card 20. The transformer is formed when thisprimary winding in the jacket 40 is mated to the secondary winding inthe smart card 20. A transformer suitable for use in coupling power intothe card from the jacket is disclosed by R. L. Billings in U.S. Pat. No.4,692,604 which issued on Sep. 8, 1987.

The CPU 430 also provides a means for providing a user interface so thata holder of the card 20 will be informed when a transaction has takenplace, either because of the information that is shown on a visualdisplay such as provided by the LCD driver 406 and LCD 405 or an audibleindication provided by a buzzer 408.

Referring next to FIG. 8, there is shown a simplified diagram forillustrating the interaction between the interrogator, the jacket andthe smart card for facilitating two-way read/write communications over aradio frequency channel. Power to the jacket 40, and thus to the card 20are turned off when these units are outside of the reception range of aninterrogation SITE associated with an interrogator. The jacket 40 thusnormally resides in a power OFF state thereby conserving battery life,in accordance with the invention.

As earlier indicated herein, the interrogator 10 continually radiates alow level interrogating signal, typically at 2.4 GHz which covers theproximate desired area of operation for each interrogation SITE. As aholder of the card enters the area of operation of the interrogationSITE, the radio frequency signal radiated by the antenna 12 of theinterrogator results in an activation signal being provided to the CPU430 in the jacket 40. Once the CPU 430 wakes up, it provides power tothe smart card 20 and also generates and sends :its own interrogationsignal to the smart card for the card to provide its identification (ID)data to the interrogator 10. The ID data provided by the card uniquelyidentifies a particular card to the interrogator 10. Upon receiving thequery, the smart card 20 generates its ID data and returns thisinformation to the interface circuitry in the jacket 40. The jacket inturn couples this ID data to the interrogator 10.

The interrogator 10 receives this ID data and then sends a channelchange command plus the ID data back to the jacket 40. As earlierindicated herein, the initial data between the jacket and theinterrogator are quickly exchanged over a special set-up RF channelreserved for that purpose. Once the initial data is exchanged theinterrogator directs the jacket to one of a plurality of RFcommunication channels wherein all subsequent and more lengthly databetween the interrogator and the jacket/card is exchanged. Thisarrangement advantageously expedites the movement of, for example,people through electronic barriers by allowing each SITE to accommodatemany simultaneous users.

To facilitate the flow of people, once each person is identified as acard user, the interrogator permits these users to quickly move past theelectronic barrier. In order to complete the transaction, however, oncethe user is through the electronic barrier, the smart card/jacket mustcontinue to communicate with the service provider. To guard against auser attempting to defraud the interrogator system by not completing therequired communications once beyond the electronic barrier and in anopen area, intelligence advantageously is included on the card and inthe interrogator system that will effectively lock the card and preventthe ID data from being subsequently read from the card in any attemptedfuture transactions. This essentially renders the card inoperative andforces the user to return the card to the service provider to reopen thecard. A card containing a security file system and suitable for lockingthe card in the manner described herein below is disclosed in U.S. Pat.No. 4,882,474.

Once the jacket has moved to one of the communication channels availableat the interrogator, the interrogator issues a read/write (R/W) commandplus the ID data back to the jacket 40. Included in this R/W command isan optional locking command that temporarily configures the card to goin a locked condition in the absence of receipt of further commands fromthe interrogator. Thus once a user is provided access beyond anelectronic barrier through generation of the ID data, the transactionwith the interrogator must be allowed to be completed or the card willbe put in a locked condition. Provided in the last R/W command of thetransaction from the interrogator to the card is a lock reset commandwhich effectively overrides the locking command previously provided fromthe interrogator to the card.

If a user is somehow capable of rendering his or her card such that itonly provides ID data out to the interrogator, this also will bedetected by the interrogator system. The data base provided by host 17will detect each incomplete transaction. It is also updatable in that itwill store the ID data then being provided thereto for comparison of anypreviously provided ID data wherein a transaction was incompleted. Foreither of these occurrences, an alerting signal is generated at anattendant's station in the vicinity of the electronic barrier forproviding an indication signal to the attendant that a bogus card isthen being used in the system.

All R/W commands are accompanied by the ID data to prevent theinterrogator 10 from erroneously affecting the data in any othersimilarly configured, nearby smart card which also might haveinadvertently, for example, moved to the wrong communication channel oris actively communicating with the interrogator 10 at a differentinterrogation SITE.

The R/W command from the interrogator may be provided in a number offorms. It may be provided in a form which debits an account in the smartcard while the holder is in the vicinity of the interrogation SITE. Whena holder uses a public transit system such as a subway, for example, thecard is initially read and the location of entry entered into the card.Then as the holder of the card leaves the subway, the appropriate amountis debited from the account in the smart card. This command may also beprovided in a form which appends to an account in the smart card.Further, The read/write command may simply allow entrance to somelimited access area or location to the holder of the card having theprovided 1D data once the holder provides some additional identifyinginformation, such as, for example, a voice print.

Once the R/W command is received from the jacket 40 by the smart card20, the appropriate action in the smart card is executed and a responsefor the interrogator 10 is generated. The jacket 40 couples the R/Wresponse along with the ID of the smart card to the interrogator 10 forproviding an indication that the appropriate action in the card has beentaken. If necessary, other commands are generated by the interrogator 10and responded to by the smart card 20. Once the final command has beenresponded to by the card 20, the interrogator sends a sleep command tothe jacket accompanied by the ID of the card and jacket. The CPU 430then turns itself, and all of the interface circuitry in the jacket 40,off. This, in turn, turns off the power to the smart card 20. The jacketis thus returned to its power OFF state.

FIG. 9 is a block diagram of an alternative interrogator system forinterfacing with multiple smart cards and radio frequency jackets. Thissystem is in the form of a parallel transmit/serial receive network. Inthis network, the interchange between the users, the SITEs 11, and thereceiver bus is similar to that described hereinbefore for the networkof FIG. 1. However, since the SITEs 11₁ to 11_(N) now transmit theformatted packets of information on separate buses 90₁ to 90_(N),respectively, to a Multiplexer/Controller (M/C) 91, the transmissionsbetween the SITEs 11 and M/C 91 are at the SITE rate and can beasynchronous. In the parallel transmit part of the network of FIG. 9,the SITEs 11₁ to 11_(N) independently deposit their packets ofinformation in buffers 913₁ to 913_(N), respectively, via respectivereceivers 914₁ to 914_(N). A sequencer and controller 915 cyclicallycontrols the sending serially of the packets of information to the host17 via the switching means 917. The packets of information are processedby the host 17 and updated information is provided from the host 17 fortransmission back to the system users. From the host 17, the packets ofinformation are coupled to a switching means 921 for loading, inparallel, of the packets of information into a very fast shift register916.

A master clock 918 in M/C 91 controls the data transfer between buffers913, switching means 917 and 921, and register 916 as well as the fastserial shifting of the bits from the frame marker generator 919 into amodulator and laser circuit 920. Frame marker generator 919 functions asdescribed for frame marker generator 18 in the interrogator 10 of FIG. 1to insert a marker at the beginning of each packet to be sent over bus14. In circuit 920, the laser is modulated by the serially receivedpacket of information from register 916. The modulated bit stream is fedinto the high-speed bus 14 where the transmission is synchronous.

Flexibility can be built, under software control, into M/C 91 formultiplexing the packets of information from the various buffers 913onto bus 14. For example, one or a fixed number of packets ofinformation from each buffer 913 could be cyclically multiplexed, oreach buffer 913 could be emptied of its packets of information beforepreceding to the next buffer. Priorities could also be easily assignedto certain buffers 913 under program control. From a hardware point ofview, the network of FIG. 9 is simpler than the serial network of FIG.1, since neither the Sense (S) and Transmit (T) directional couplers northe laser 116 and very fast shift register 115 in the transmitter ofeach SITE 11 are needed. The lower speed of the parallel transmissionson buses 40₁ to 40_(N) of FIG. 9 permits the use of, for example,multimode fibers and LED sources for the lightwave network of FIG. 9.The only disadvantage is the need for more buses in the paralleltransmit connection. The very high-speed components, however, wouldstill be needed in the receiver sections of the SITEs 11 of FIG. 9 aswell as in M/C 91, which is shared by all SITEs 11.

It is to be understood that the above-described embodiments are simplyillustrative of the principles of the invention. Various othermodifications and changes may be made by those skilled in the art whichwill embody the spirit and scope thereof. For example, the interrogatorsystem can be adapted to interrogate items being moved on a conveyerbelt, freight boxcars as they move in and out of freight yards, and longhaul trucks at weight stations, etc. All that is necessary is to have asmart card/jacket affixed to the desired unit and have this unit passwithin the proximity of an interrogation SITE for the interrogator. Thusother applications to smart cards, computers or other user interrogationsystems other than the disclosed system are contemplated as being withinthe knowledge of one skilled in the art and may be utilized withoutdeparting from the spirit and scope of the present invention.

I claim:
 1. An interrogator for remotely interrogating a portable datacard, the interrogator being operable over a plurality of radiofrequencies and comprising:means for communicating with the portabledata card on a first one of the plurality of radio frequencies fordetermining a unique identification number associated with the datacard; means for initiating a predetermined transaction responsive toreceipt of the unique identification number by the interrogator; meansfor completing the predetermined transaction while communicating withthe card on a second one of the plurality of radio frequencies, theinterrogator reading data from and writing data to the card whileoperating over said second one of the plurality of radio frequencies;and means for transmitting a locking command and a subsequent lock resetcommand to the card, the locking command being registered in the cardand being disabled by the lock reset command issued by the interrogatorin response to the interrogator completing the predeterminedtransaction.
 2. The interrogator of claim 1 wherein the initiation meansincludes activation means for gaining access to a limited access area,the activation means deactivating an electronic barrier to entering saidlimited access area.
 3. The interrogator of claim 1 wherein a firstread/write command from the interrogator to the card in a transactionincludes the locking command.
 4. The interrogator of claim 3 wherein alast read/write command from the interrogator to the card in atransaction includes the lock reset command.
 5. The interrogator ofclaim 4 wherein in the absence of the predetermined transaction beingcompleted by the completion means, the locking command remainsregistered in the card for disabling the card.
 6. In an interrogationsystem for remotely interrogating a plurality of portable data cards, aninterrogator operable over a plurality of radio frequencies andcomprising:means for sequentially communicating with each portable datacard on a first one of the plurality of radio frequencies fordetermining a unique identification number associated with each datacard; means for initiating a predetermined transaction for each cardresponsive to receipt of said unique identification number associatedwith each card by the interrogator; and means for completing thepredetermined transaction while respectively communicatingsimultaneously with each card on a different selected one of theplurality of radio frequencies, the interrogator reading data from andwriting data to each card while operating on said selected one of theplurality of radio frequencies.
 7. The interrogation system of claim 6wherein the initiation means includes activation means for gainingaccess to a limited access area, the activation means deactivating anelectronic barrier to entering said limited access area.
 8. A method ofremotely interrogating a portable data card from an interrogationstation, the interrogation station being operable over a plurality ofradio frequencies, the method comprising the steps of:communicating withthe portable data card on a first one of the plurality of radiofrequencies for determining a unique identification number associatedwith the data card; initiating a predetermined transaction responsive toreceipt of the unique identification number by the interrogationstation; completing the predetermined transaction while communicatingwith the card on a second one of the plurality of radio frequencies; andtransmitting a locking command to the card and transmitting a subsequentlock reset command to the card, the locking command initially beingregistered in the card upon receipt and being disabled in the card uponreceipt of the lock reset command, the lock reset command being issuedby the interrogation station in response to the interrogation stationcompleting the predetermined transaction.
 9. The method of claim 8wherein the initiation step includes the step of deactivating anelectronic barrier for gaining access to a limited access areacontrolled by said barrier.